package 数据结构;

import java.util.Arrays;
import java.util.Objects;

/**
 * @author 乐心湖
 * @date 2020/6/15 12:16
 **/
public class Array<E> {
    private E[] data;
    private int size;

    //默认数组容量为20
    public Array() {
        this(10);
    }

    //用户自定义数组容量
    public Array(int capacity) {
        data = (E[]) new Object[capacity];
        size = 0;
    }

    //获取数组元素的个数
    public int getSize() {
        return size;
    }

    //获取数组容量
    public int getCapacity() {
        return data.length;
    }

    //数组是否为空
    public boolean isEmpty() {
        return size == 0;
    }

    //向数组末尾添加一个新元素
    public void addLast(E e) {
        add(size, e);
    }

    //向数组首位添加一个新元素
    public void addFirst(E e) {
        add(0, e);
    }

    //在某个位置插入一个新元素
    public void add(int index, E e) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("AddLast failed. index < 0 || index > size");
        }
        if (size == data.length) {
            resize((2 * data.length));
        }
        for (int i = size - 1; i >= index; i--) {
            data[i + 1] = data[i];
        }

        data[index] = e;
        size++;
    }

    //获取index索引位置的元素
    E get(int index) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("Get failed. Index is illegal");
        }
        return data[index];
    }

    //修改index索引位置的元素e
    void set(int index, E e) {
        if (index < 0 || index > size) {
            throw new IllegalArgumentException("Get failed. Index is illegal");
        }
        data[index] = e;
    }

    //查找数组是否有元素e
    public boolean contains(E e) {
        for (int i = 0; i < size; i++) {
            if (data[i].equals(e)) {
                return true;
            }
        }
        return false;
    }

    //查找数组中元素e所在的索引，如果不存在，返回-1
    public int find(E e) {
        for (int i = 0; i < size; i++) {
            if (data[i].equals(e)) {
                return i;
            }
        }
        return -1;
    }

    //删除index索引的元素，返回删除的元素
    public E remove(int index) {
        if (index < 0 || index >= size) {
            throw new IllegalArgumentException("Remove failed. INdex is illegal");
        }
        E ret = data[index];
        for (int i = index + 1; i < size; i++) {
            data[i - 1] = data[i];
        }
        size--;
        data[size] = null;
        if (size == data.length/2){
            resize(data.length/2);
        }
        return ret;
    }

    public E removeFirst() {
        return remove(0);
    }

    public E removeLast() {
        return remove(size - 1);
    }

    public boolean removeElement(E e) {
        int index = find(e);
        if (index != -1) {
            remove(index);
            return true;
        }
        return false;
    }

    @Override
    public String toString() {

        StringBuilder res = new StringBuilder();
        res.append(String.format("Array: size = %d , capacity = %d\n", size, data.length));
        res.append("[");
        for (int i = 0; i < size; i++) {
            res.append(data[i]);
            if (i != size - 1)
                res.append(", ");
        }
        res.append("]");
        return res.toString();
    }

    private void resize(int newCapacity) {
        E[] newData = (E[]) new Object[newCapacity];
        for (int i = 0; i < size; i++) {
            newData[i] = data[i];
        }
        data = newData;
    }
}
